docs: def get_rx_distance(self, mesh):
          """
          For each point determine the corresponding rx distance using the GC2
          configuration.
  
          See :meth:`superclass method
          <.base.BaseSurface.get_rx_distance>`
          for spec of input and result values.
          """
          # If the GC2 calculations have already been computed (by invoking Ry0
          # first) and the mesh is identical then class has GC2 attributes
          # already pre-calculated
          if not self.tmp_mesh or (self.tmp_mesh == mesh):
              self.gc2t, self.gc2u = self.get_generalised_coordinates(mesh.lons,
                                                                      mesh.lats)
              # Update mesh
              self.tmp_mesh = deepcopy(mesh)
          # Rx coordinate is taken directly from gc2t
          return self.gc2t